It's a great question. There are a couple of parts to it. I'm going to address the first part regarding the privacy of the buyer.
There is a new concept called “zero knowledge proof”. It's pretty mathematical, so I won't get into the details. Essentially, it allows someone to verify that the seller actually has the product and has sold it to the buyer, without revealing any of the details of the buyer. There is a way to have these transactions done in privacy. It's one of the innovations in blockchain that has really revolutionized the way that things are done. It's very, very new. There are very few actual implementations in production right now. However, zero knowledge proof is exactly a way that you can buy and sell art by protecting the identify of the buyer.
To your second question as to how the payment would work, this is through something called a “smart contract”. A smart contract is essentially code that is written into the blockchain that will transact without an intermediary coming in there. What that means is that any time there is an actual sale from a seller to a buyer, the smart contract would be triggered to take a percentage of the payment from the buyer and input it into a registry for resale rights.